The project is designed to extend previous studies concerning the characterization of the rRNA-modification enzyme(s), rRNA-adenine (N6-) methylase(s) of E. coli strain K12, which are responsible for the synthesis of N6-methyladenine moieties within two unique sequences of 23s rRNA. Continued efforts will be made to determine whether the synthesis of the two N6-methyladenine moieties, one occurring early and one occurring late in the ribosomal assembly process, requires one or two methylase entities. If two are involved, emphasis will be directed toward their physical separation and the correlation of the methylase with the unique N6-methyladine moiety it synthesizes. Each methylase will be further characterized as to (a) the properties of the methylase which contribute to its ability to bind to rRNA and select an appropriate oligonucleotide sequence, (b) the minimal size, conformation, and presence/absence of ribosomal proteins at the recognition/methylation site, and (c) the mechanism by which ppGpp modulates the activity of the methylase(s).